[libc-commits] [libc] [libc] Simple __stack_chk_guard implementation (PR #78804)
via libc-commits
libc-commits at lists.llvm.org
Fri Jan 19 15:11:42 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libc
Author: Petr Hosek (petrhosek)
<details>
<summary>Changes</summary>
This is needed on systems that don't use TLS to store the stack canary.
---
Full diff: https://github.com/llvm/llvm-project/pull/78804.diff
11 Files Affected:
- (modified) libc/config/baremetal/arm/entrypoints.txt (+1)
- (modified) libc/config/baremetal/riscv/entrypoints.txt (+1)
- (modified) libc/config/linux/aarch64/entrypoints.txt (+1)
- (modified) libc/config/linux/arm/entrypoints.txt (+8)
- (modified) libc/src/compiler/CMakeLists.txt (+15-2)
- (added) libc/src/compiler/__stack_chk_guard.h (+20)
- (added) libc/src/compiler/baremetal/CMakeLists.txt (+7)
- (added) libc/src/compiler/baremetal/__stack_chk_guard.cpp (+17)
- (added) libc/src/compiler/linux/CMakeLists.txt (+11)
- (added) libc/src/compiler/linux/__stack_chk_guard.cpp (+39)
- (modified) libc/test/src/compiler/CMakeLists.txt (+1)
``````````diff
diff --git a/libc/config/baremetal/arm/entrypoints.txt b/libc/config/baremetal/arm/entrypoints.txt
index f725b1c2394c6a3..39f54440780deb8 100644
--- a/libc/config/baremetal/arm/entrypoints.txt
+++ b/libc/config/baremetal/arm/entrypoints.txt
@@ -19,6 +19,7 @@ set(TARGET_LIBC_ENTRYPOINTS
# compiler entrypoints (no corresponding header)
libc.src.compiler.__stack_chk_fail
+ libc.src.compiler.__stack_chk_guard
# errno.h entrypoints
libc.src.errno.errno
diff --git a/libc/config/baremetal/riscv/entrypoints.txt b/libc/config/baremetal/riscv/entrypoints.txt
index 5da755170fda96e..79bd24bea103aea 100644
--- a/libc/config/baremetal/riscv/entrypoints.txt
+++ b/libc/config/baremetal/riscv/entrypoints.txt
@@ -19,6 +19,7 @@ set(TARGET_LIBC_ENTRYPOINTS
# compiler entrypoints (no corresponding header)
libc.src.compiler.__stack_chk_fail
+ libc.src.compiler.__stack_chk_guard
# errno.h entrypoints
libc.src.errno.errno
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 625fa6bffe63c65..7496947a781bd4f 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -366,6 +366,7 @@ if(LLVM_LIBC_FULL_BUILD)
list(APPEND TARGET_LIBC_ENTRYPOINTS
# compiler entrypoints (no corresponding header)
libc.src.compiler.__stack_chk_fail
+ libc.src.compiler.__stack_chk_guard
# network.h entrypoints
libc.src.network.htonl
diff --git a/libc/config/linux/arm/entrypoints.txt b/libc/config/linux/arm/entrypoints.txt
index c75ac2302d4ac45..7070f6c4e5a1521 100644
--- a/libc/config/linux/arm/entrypoints.txt
+++ b/libc/config/linux/arm/entrypoints.txt
@@ -235,6 +235,14 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.truncl
)
+if(LLVM_LIBC_FULL_BUILD)
+ list(APPEND TARGET_LIBC_ENTRYPOINTS
+ # compiler entrypoints (no corresponding header)
+ libc.src.compiler.__stack_chk_fail
+ libc.src.compiler.__stack_chk_guard
+ )
+endif()
+
set(TARGET_LLVMLIBC_ENTRYPOINTS
${TARGET_LIBC_ENTRYPOINTS}
${TARGET_LIBM_ENTRYPOINTS}
diff --git a/libc/src/compiler/CMakeLists.txt b/libc/src/compiler/CMakeLists.txt
index aa59d84e08d1467..b37b2dbe1c61989 100644
--- a/libc/src/compiler/CMakeLists.txt
+++ b/libc/src/compiler/CMakeLists.txt
@@ -1,9 +1,9 @@
if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
-else()
- add_subdirectory(generic)
endif()
+add_subdirectory(generic)
+
if(TARGET libc.src.compiler.${LIBC_TARGET_OS}.__stack_chk_fail)
set(stack_chk_fail_dep libc.src.compiler.${LIBC_TARGET_OS}.__stack_chk_fail)
else()
@@ -16,3 +16,16 @@ add_entrypoint_object(
DEPENDS
${stack_chk_fail_dep}
)
+
+if(TARGET libc.src.compiler.${LIBC_TARGET_OS}.__stack_chk_guard)
+ set(stack_chk_guard_dep libc.src.compiler.${LIBC_TARGET_OS}.__stack_chk_guard)
+else()
+ set(stack_chk_guard_dep libc.src.compiler.generic.__stack_chk_guard)
+endif()
+
+add_entrypoint_object(
+ __stack_chk_guard
+ ALIAS
+ DEPENDS
+ ${stack_chk_guard_dep}
+)
diff --git a/libc/src/compiler/__stack_chk_guard.h b/libc/src/compiler/__stack_chk_guard.h
new file mode 100644
index 000000000000000..17edefa3465d7e5
--- /dev/null
+++ b/libc/src/compiler/__stack_chk_guard.h
@@ -0,0 +1,20 @@
+//===-- Internal header for __stack_chk_guard -------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_COMPILER___STACK_CHK_GUARD_H
+#define LLVM_LIBC_SRC_COMPILER___STACK_CHK_GUARD_H
+
+#include <stdint.h>
+
+// The compiler will emit calls implicitly to a non-namespaced version.
+// TODO: can we additionally provide a namespaced alias so that tests can
+// explicitly call the namespaced variant rather than the non-namespaced
+// definition?
+extern "C" uintptr_t __stack_chk_guard;
+
+#endif // LLVM_LIBC_SRC_COMPILER___STACK_CHK_GUARD_H
diff --git a/libc/src/compiler/baremetal/CMakeLists.txt b/libc/src/compiler/baremetal/CMakeLists.txt
new file mode 100644
index 000000000000000..222ca9fc1523671
--- /dev/null
+++ b/libc/src/compiler/baremetal/CMakeLists.txt
@@ -0,0 +1,7 @@
+add_entrypoint_object(
+ __stack_chk_guard
+ SRCS
+ __stack_chk_guard.cpp
+ HDRS
+ ../__stack_chk_guard.h
+)
diff --git a/libc/src/compiler/baremetal/__stack_chk_guard.cpp b/libc/src/compiler/baremetal/__stack_chk_guard.cpp
new file mode 100644
index 000000000000000..691e0c4f725220f
--- /dev/null
+++ b/libc/src/compiler/baremetal/__stack_chk_guard.cpp
@@ -0,0 +1,17 @@
+//===-- Implementation of __stack_chk_guard -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/compiler/__stack_chk_guard.h"
+
+#include <stdint.h>
+
+extern "C" {
+
+uintptr_t __stack_chk_guard = 0x00000aff; // 0, 0, '\n', 255
+
+} // extern "C"
diff --git a/libc/src/compiler/linux/CMakeLists.txt b/libc/src/compiler/linux/CMakeLists.txt
new file mode 100644
index 000000000000000..33918fb2f4db28c
--- /dev/null
+++ b/libc/src/compiler/linux/CMakeLists.txt
@@ -0,0 +1,11 @@
+add_entrypoint_object(
+ __stack_chk_guard
+ SRCS
+ __stack_chk_guard.cpp
+ HDRS
+ ../__stack_chk_guard.h
+ DEPENDS
+ libc.src.__support.OSUtil.osutil
+ COMPILE_OPTIONS
+ -Wno-global-constructors
+)
diff --git a/libc/src/compiler/linux/__stack_chk_guard.cpp b/libc/src/compiler/linux/__stack_chk_guard.cpp
new file mode 100644
index 000000000000000..112dd2a52da70cd
--- /dev/null
+++ b/libc/src/compiler/linux/__stack_chk_guard.cpp
@@ -0,0 +1,39 @@
+//===-- Implementation of __stack_chk_guard -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/compiler/__stack_chk_guard.h"
+#include "src/__support/OSUtil/syscall.h"
+#include "src/errno/libc_errno.h"
+
+#include <sys/syscall.h>
+
+extern "C" {
+
+uintptr_t __stack_chk_guard = 0;
+
+} // extern "C"
+
+namespace LIBC_NAMESPACE {
+namespace {
+
+class StackCheckGuard {
+public:
+ StackCheckGuard() {
+ // TODO: Use getauxval(AT_RANDOM) once available.
+ long retval =
+ syscall_impl(SYS_getrandom, reinterpret_cast<long>(&__stack_chk_guard),
+ sizeof(uintptr_t), 0);
+ if (retval < 0)
+ __stack_chk_guard = 0x00000aff; // 0, 0, '\n', 255
+ }
+};
+
+StackCheckGuard stack_check_guard;
+
+} // anonymous namespace
+} // namespace LIBC_NAMESPACE
diff --git a/libc/test/src/compiler/CMakeLists.txt b/libc/test/src/compiler/CMakeLists.txt
index 65a9acceb6f7f10..39f96eb2272431a 100644
--- a/libc/test/src/compiler/CMakeLists.txt
+++ b/libc/test/src/compiler/CMakeLists.txt
@@ -9,6 +9,7 @@ add_libc_unittest(
DEPENDS
libc.src.__support.macros.sanitizer
libc.src.compiler.__stack_chk_fail
+ libc.src.compiler.__stack_chk_guard
libc.src.string.memset
COMPILE_OPTIONS
-fstack-protector-all
``````````
</details>
https://github.com/llvm/llvm-project/pull/78804
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